Starting a TQ rebuild - tips and tricks?

[halfafish]

I am not carb competent. In fact, carbs = kryptonite in my world. So far in life I rebuilt the Holley 1920 on my Valiant and that's it. That adventure was successful but I know I'm heading into far more complicated and uncharted territory.

My 72 Coronet wagon is a dead stock 318 2- barrel. I'm converting to 4-barrel and want to go through the carb before doing the install. I have a 72 Factory TQ intake, 72 340 HP exhaust manifolds (it will get dual exhaust), Speedmaster heads, and all the kickdown parts. I'll be doing a better cam (that will be another thread) with a new double timing set but that will be down the road while I work on the above parts. The goal is a nice cruiser, I'm not trying to make a monster out of this.

I have this 6139S carb, and this rebuild kit.

Obviously the carb is used, but it looks to be in nice condition. It's clean, everything moves OK, and I don't feel any slop in anything. I have the FSM for this car, and will also be using this book for the rebuild.

I am soliciting any help from the group before I dive into this. I know I'm going WAY above my skillset giving this a shot. Any hints, tips, tricks, additional reference material, or "don't do that" info will be warmly welcomed.

TIA!!

 

[Newbomb Turk]

You may want to look at the modifications and tips that Chrysler put in the big book years ago.

Other than dealing with todays shitty pump fuel (especially shitty for carbs) those mods work very well.

I’m not sure that stuff is in the newest small block engine book. It may be but I know it’s in my 1980 and 1990 something books

 

[Professor Fate]

I'm sure you've already read RRR's TQ rebuild writeup in the "Articles" section? A good read.
Thermoquad Teardown and Reassembly How To

 

[ch1ll]

You have to be careful taking it apart that you don’t damage the phenolic resin fuel body. Other than that,make sure the butterfly shafts are not loose. There are bushing kits to repair them if they are loose from wear. Rebuild is fairly simple, its the tuning that is the time consuming part and parts are hard to come by.

There are folks that specialize in rebuilding them and that is what I would do.

 

[CFD244]

Don't forget the 2 hidden screws inside the primary air horn before you start trying to pry it apart.

 

[66fs]

You should be good with that carb leave the factory jetting and rods. About the only thing you should need to do is adjust the secondary air valve to open as quickly as you can without a bog. First carefully remove the bowl so you do not break off the alignment pins on the bottom of the bowl. Second problem area is the primary jet inserts sometimes strip in the plastic. Third are the fuel wells, make sure they do not leak while you have the bowl separate. Then, just your basic rebuild. Take pictures and take your time.

 

[remytherat]

Don't forget the 2 hidden screws inside the primary air horn before you start trying to pry it apart.

But it wouldn’t be a true first TQ rebuild without this canon event

 

[Bewy]

[1] If you want to improve the secondary performance, look for the thread in my name in this section, early Oct last year. The sec mod gives the carb a big WAKE UP call.

[2] As mentioned, the caps under the pri jets are sealed with white epoxy. They leak over time & it is very hard to see any cracks.....or diagnose the problem.

Since you are rebuilding, these should be re-sealed. Using a small hacksaw blade or triangular shaped modeller's file, grind out the old epoxy so that you have a slight depression. You can go deep enough that the cap comes off, but not necessary.
Use petrol proof epoxy [ I use Devcon ] around the caps to re-seal. Do not use big blobs, otherwise the gasket may not fit; if this happens, trim the epoxy.
[3] I would replace the air valve diaphragm, mounted passengers side rear. The rubber goes hard after time & can cause some hard to diagnose problems.
[4] Also get a leather acc pump plunger. They are more positive, last forever.
[5] Set a/valve spring to 1.5 turns.
[6] Sec high speed air bleed. The rod that goes down the centre of the sec jet. Make sure the hole in the top of the HSAB is 0.039-0.040" [ it probably will be already ].
[7] If you get any surging at cruise at higher rpms [ on the cruise step of the m/rods] try & find some rods with a 069 or 067 cruise step [ 1962, 1966, 1965 ]

 

[66fs]

I would not do any mods to that carb. They were so good as they came for a "72" 340.

 

[GTX JOHN]

I have over 100 thermoquad and tons of
spare parts. PM for any questions but Bewy
pretty much cover it!